Implantable vascular access device with ceramic needle guard insert

ABSTRACT

The present invention provides an improved vascular access port comprising a port base with a metallic dish insert molded (or bonded) into the bottom of the reservoir. In one embodiment, a single reservoir is provided. In another embodiment, plural reservoirs are provided. The metallic bottom of the reservoir provides a hard surface that will resist abrasion and puncture by the access needles used to infuse medication or withdraw blood. Additionally, the single and dual ports can include exit ports that are intended to better anatomically fit into the subcutaneous areas around muscle tissue.

This application is a continuation application of application Ser. No.09/582,406, filed Jun. 23, 2000, now U.S. Pat. No. 6,527,754, whichclaims priority from PCT Application Serial No. PCT/US99/28695, filedDec. 3, 1999, which claims priority from U.S. Provisional ApplicationSer. No. 60/111,257, filed Dec. 7, 1998, all of which are incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a subcutaneously implantablevascular access port. More specifically, the present invention relatesto an access port having a single needle-penetrable, self-sealing septumwhich affords repeated access to a plurality of distinct fluid cavitieshaving staggered outlet ducts in communication with a plural lumencatheter.

2. Description of Related Art

Access portals, or ports, provide a convenient method to repeatedlydeliver medicants to remote areas of the body without utilizing surgicalprocedures. The port is totally implantable within the body, and permitsthe infusion of medications, parenteral solutions, blood products, andother fluids. The port may also be used for blood sampling.

Known ports typically include a chamber accessible through aself-sealing septum. Septums of the prior art vary in shape, from awafer-like cylindrical block of silicone to a pre-molded septum of U.S.Pat. No. 4,802,885 to Weeks et al. The pre-molded septum of U.S. Pat.No. 4,802,885 includes opposed convex surfaces and a peripheral ledge.

In common practice, a caregiver locates the septum of the port bypalpitation. Port access is accomplished by percutaneously inserting aneedle, typically a non-coring needle, perpendicularly through theseptum of the port and into the chamber. The drug or fluid is thenadministered by bolus injection or continuous infusion. Ordinarily thefluid flows through the chamber, into a catheter and finally to the sitewhere the fluid is desired. Except for the septum, traditional ports areconstructed from all-metal or all-plastic. Each type of construction hasunique advantages and disadvantages.

All-metal constructions have the advantages that they maintain a septumin a self-sealing fashion after repeated percutaneous injections.Additionally, all-metal constructions, such as titanium, or stainlesssteel provide a port which is both biocompatible and compatible with theinjected fluid.

However, all-metal constructions present the disadvantages that they arerelatively heavy, difficult to fabricate and relatively expensive.Additionally, all-metal ports produce large Magnetic Resonance Imaging(MRI) artifacts. On the other hand, all-plastic ports have theadvantages that they are inexpensive to construct, light in weight, anddo not create an MRI artifact. However, ports constructed from plastichave the disadvantage that infused fluids may react with the plasticbody of the port. All-plastic ports contain the disadvantage that theycannot maintain a sealing engagement with the septum after repeatedpercutaneous injections. Additionally, all-plastic ports are susceptibleto nicks and scratches on the interior surface by the accessing needle.These nicks and scratches could lead to nidus, blood clots, orprecipitation formations.

Efforts have been made to combine the advantages of all-metal ports withall-plastic ports. For example, in U.S. Pat. No. 4,802,885 to Weeks etal., a metal reservoir having a chamber sealed by a pre-formed siliconeseptum is jacketed by a single piece of a silicone elastomer. However,all-metal ports jacketed by a single piece of elastomer have significantshortcomings. These shortcomings include quality control problems duringmanufacturing, and expensive molding processes.

Other efforts have focused on providing a multiple piece all-plastichousing in cooperation with an open metal cup to sealingly engage aseptum. For example, see U.S. Pat. No. 5,213,574 to Tucker. This designhas shortcomings associated with it, including defects in the plastichousing which may cause an improperly sealed septum. Once the septum isimproperly sealed the entire port must be discarded.

Therefore a need has arisen for an access port device which addressesthe problems of prior port devices.

A variety of implantable devices, known as subcutaneous access ports,are utilized to deliver fluids to or to withdraw fluids from thebloodstream of a patient. Such access ports typically include aneedle-impenetrable housing which encloses one or more fluid cavitiesand defines for each such fluid cavity an access aperture communicatingthrough the housing on the side thereof which is adjacent to the skin ofthe patient when the access port is implanted in the body. Aneedle-penetrable septum is received in and seals each access aperture.Exit passageways located in an outlet stem communicate with each of thefluid cavities for dispensing medication therefrom to a predeterminedlocation in the body of the patient through an implanted catheterattached to the access port.

Once the access port and the catheter have been implanted beneath theskin of a patient, quantities of medication or blood may be dispensedfrom one such fluid cavity by means of a non-coring needle passedthrough the skin of the patient and penetrating the septum into one ofthe respective fluid cavities. This medication is directed through thedistal end of the catheter to an entry point into the venous system ofthe body of the patient.

Blood may also be withdrawn for sampling from the body of a patientthrough such an access port. This is accomplished by piercing the skinof the patient and one of the respective septums with a non-coringneedle and applying negative pressure thereto. This causes blood to bedrawn through the catheter into the fluid cavity corresponding to thepierced septum and then out of the body of the patient through theneedle.

To prevent clotting thereafter, the withdrawal route is flushed with asaline solution or heparin using again a non-coring needle piercing theskin of the patient and the septum in the same manner as if a medicationwere being infused.

Both intermittent and continual injections of medication may bedispensed by the access port. Continual access involves the use of anon-coring needle attached to an ambulatory-type pump or a gravity feedIV bag suspended above the patient. The ambulatory-type pump or the IVbag continually feeds the medication or fluid through the needle to thefluid cavity in the access port and from there through the catheter tothe entry point into the venous system.

To facilitate locating each respective septum once the access port hasbeen implanted, some access ports incorporate a raised circular ringlocated about the outer perimeter of the septum. This raised ringenhances the tactile sensation afforded by the subcutaneous septum tothe palpating fingertip of a medical practitioner. Alternatively, otheraccess ports have utilized palpation ridges rather than a raisedcircular ring for substantially the same purpose. The palpation ridgesallow the location of the septum to be accurately determined when theaccess port is subcutaneously implanted.

To preclude reaction with the tissues in the body of the patient, accessports are constructed of nonreactive materials, such as titanium orstainless steel. Although these materials are nonreactive, access portsconstructed utilizing titanium or stainless steel materials produce aninterfering or blurred image of the body of the patient in the vicinityof the implanted access port when diagnostic imaging techniques such asmagnetic resonance imaging (“MRI”), CAT scans, or computerizedtomography are used. The blurred region caused by the presence of ametallic access port in the body of a patient extends beyond the accessport itself. Therefore, the use of metallic access ports limits thediagnostic imaging techniques that may be used relative to those areasof the body in which an access port is implanted. In place of metallicmaterials some access ports have been fabricated at least in part frombiocompatible plastics.

A further problem relating to the materials for and manufacture ofaccess ports is the deleterious impact of some manufacturing procedureson the fluids which flow through the fluid cavities and relatedstructures located between the fluid cavities and the catheter. Duringthe manufacture of an access port, whether the port is comprised ofmetallic or plastic materials, it becomes necessary to form the fluidcavities and exit passageways through which the fluid will be directedinto the attached catheter. This manufacturing process often leavessharp edges, seams and corners in the areas where the fluid cavity is todirect the flow of the fluid through an exit passageway. As blood orother fluids are injected through the septum into the fluid cavity,pressure developed within the fluid cavity tends to cause fluid to flowthrough the exit passageway. As the fluid in the fluid cavity flows pastthe sharp edges and corners produced in the manufacture of the accessport, turbulence arises, taking the form of a vortex, adjacent to thesharp edges and corners. Some fluids, such as blood, are sensitive tothis turbulence, and lysing of the red blood cell component of theinjected blood can occur in these turbulent areas.

In addition, the production of the circular fluid cavities often resultsin the creation of areas within the housing in which fluid flow isretarded. These areas are referred to as dead spaces and usually occurin areas of transition, such as where the bottom of the septuminterfaces with the walls of the fluid cavity and where the floor of thefluid cavity meets the exit passageway through which the fluid mustflow. As the flow of fluids through dead spaces is retarded, stagnationoccurs, resulting in some fluid being trapped within these dead spaces.If the access port is used to withdraw or transfuse blood, blood trappedin these dead spaces may form clots and block the flow of fluid throughthe fluid cavity.

Moreover, in some prior vascular access ports the internal reservoirsare formed by two plastic parts with are bonded together. This resultsin an undesirable seam being formed where the adjacent parts abut oneanother. The inside of the reservoir should be as smooth as possible tohelp prevent damage to blood cells or the initiation of blood clottingduring infusion or withdrawal of blood through the port.

A further problem encountered in the design and construction of accessport relates to the positioning of the septums within the housing of theaccess port. The positioning of the septums within the housing is acompromise between two conflicting objectives. These are the need toseparate the septums to such a distance so that the septums may beeasily differentiated for the purpose of injection and the need torestrict the overall dimensions of the access port for patient comfortand aesthetics. The distancing of the septums to facilitate theirdifferentiation, however, results in a corresponding distancing of thefluid cavities. This result is at odds with another structuralrequirement for access ports with plural cavities, namely that the exitpassageways from each fluid cavity be closely spaced at the point wherethe implanted catheter is to be coupled to the access port.

To guide the flow of a fluid from each of the spatially separated fluidcavities into the side-by-side configuration of fluid outflownecessitated by the dimensions of a plural lumen catheter, intermediatestructural members have been required. Naturally, this complicates theprocess of manufacture and increases its cost, as well as the changes ofstructural failure.

There are several examples of such intermediate members used to resolvethe manufacturing constraints imposed upon the construction of apassageway flowing from spatially separate fluid cavities into aside-by-side configuration acceptable by a catheter. One is to producepassageways in the form of bent metal tubes which are then insert moldedor welded into the larger body of the access port. The use of such ametal component will interfere with the production of an access portwhich is free of limits as to the diagnostic imaging techniques that maybe used relative to those areas of the body in which an access port isimplanted. In addition, the integral nature of such metal outletpassageways raises the possibility of leakage of medication through theinterstices between the metal tubes and the body of the access port.

Alternatively, to produce fluid flow from spatially separated fluidcavities into the closely spaced lumens of a catheter, each fluid cavityhas been designated with its own spatially separated outlet stem. Theseoutlet stems are then coupled by a hub structure for permanentattachment to the closely spaced lumens of a catheter. This type ofarrangement increases the size of the overall access port and its costof manufacture by adding thereto the necessity of fabricating andassembling of the hub element. Port connections to catheters in thismanner are permanent. Accordingly, if the catheter is to be shortened bytrimming, that trimming must occur at the distal end of the catheter,and this precludes the use of any type of specially designed tip orvalve.

An additional set of problems encountered in the use of access portsrelates to the actual connection of the catheter to the access port.This is most commonly effected by securing the catheter to an outletstem protruding from the housing of the access port. In an attempt tolock the catheter to the outlet stem of the access port, thread-typesystems have been developed wherein the catheter is attached to anoutlet stem, and the outlet stem is then threaded into the access port.When utilizing this system, however, it is difficult to determine theamount of engagement of the catheter onto the outlet stem. Some catheterconnection systems do not allow visual verification of attachment. As aresult, leakage and failure can occur.

To overcome this problem, access ports are produced in which thecatheter is pre-attached at the factory. While this practice alleviatesmany of the problems with leakage and failure due to catheter slippage,this system severely limits the type of the catheter usable with theaccess port. This precludes the use of catheters having specializeddistal tips, as the distal end of the catheter is the only end that canthen be trimmed to effect its ultimate sizing. For example, cathetersutilizing a Groshong.RTM. slit valve at their distal end may not haveany of the distal tip of the catheter removed without compromising thecatheter.

Thus, there has been a need for an improved vascular access port whichovercomes the above-noted problems, and which can be manufacturedeconomically. The present invention fulfills these needs and providesother related advantages.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides an improved vascular accessport comprising a plastic port base with a metallic dish insert molded(or bonded) into the bottom of the reservoir. In one embodiment, asingle reservoir is provided. In another embodiment, plural reservoirsare provided. The metallic bottom of the reservoir provides a hardsurface that will resist abrasion and puncture by the access needlesused to infuse medication or withdraw blood. The features of both thesingle and dual ports include ‘duck tail’ rears. This feature isintended to better anatomically fit into the subcutaneous areas aroundmuscle tissue. The plastic must be of a bio-compatible andchemically-compatible material such as Nylon, Poly Acetals, orPolyethersulphone. The chemical resistance is necessary so that theinjected medications do not react with the port materials. The yield andcreep strength and flexure modulus of the material is important so thatthe plastic will hold and retain the port top retaining the septum.

In the preferred embodiment, the present invention provides animplantable access port, comprising a housing member defining at leastone fluid chamber. A cup member is attached to the housing member anddefining the bottom of the fluid chamber. A permeable septum member isattached to the housing and defining the top of the fluid chamber andhaving a tactile or visual location marker portion on the outer surfacethereof. An exit port is provided to permit egress of fluid from withinthe fluid chamber.

The cup may be made of stainless steel, titanium or ceramic (alumina orzirconium). All these materials are biologically and chemically inert sothat they will not react with the body or medications. The insert isformed, cast, machined or molded into a ‘dish’ shape with the edgesbeing of a radius greater than 0.035″. This radius is important for thereduction of coagulation and turbulence of the blood and medicationwithin the reservoir.

The port assembly can include a top or retaining ring(s). This topretains the rubber septum. It can be made of the same plastic materialas the base; in which case, it can be fit, bonded or ultra-sonicallywelded to the base after septum placement. It can be a metallic materialas mentioned above for the dish insert. For these applications theattachment of the top can be achieved by interference fits, bonding witha biocompatible epoxy or by various welding means (ultrasonic, friction,or thermal melt).

Each port has a stem or catheter adapter which enables a fluid pathbetween the reservoir and the external catheter traveling to thevascular area. Stems are made from biocompatible and chemically inertmaterials that are also strong such as stainless steel or titanium. Thestem for the single port has one fluid channel straight through itsbody. The dual version has two channels which angle out to the sides inorder to meet with the walls of the reservoirs. Both these stems havebarbs for locking into the plastic body. Barb(s) are also found on thedistal end for attachment to the catheter. The dual version has a splitbetween the channel holes in order to allow a bi-lumen catheter toattach.

The septums for these ports are intended to assist in the location (andin the case of the dual port) differentiation of the reservoir location.The combinations for these may vary for application preferences. The twostyles include concave and convex shapes. After the surgicalimplantation, the location is determined by palpitation of the skin overthe port. For the illustration shown, the concave side feels differentthan the convex side. The convex feature has a nipple shape. Bothseptums are designed to fit into the port body and be retained by theport top. The septum is intended to be self sealing under the pressuresproduced by the vascular system and the injection pressures ofinjections. This is achieved by controlling the rubber hardness and thedimensions relative to the retained assembly. The interference fit orsqueezing of the septum rubber creates a residual pressure radiallytoward the center of the septum. The softness of the rubber allows thepunctures to reseal without leakage. It is preferred that non-coringneedles are used by clinical staff to avoid excessive reduction ofmaterial and coring or skiving material into the reservoir which flowinto the blood stream. The rubber material commonly used for septums issilicone, but other biocompatible elastomer materials may be used.

Advantageously, the present invention provides low cost, yet durablesubcutaneous vascular access port(s). The port(s) can be manufacturedfrom bicompatible grades of plastics and metals which meets the safetyand clinical parameters of implanted devices. This plastic port featuresa metallic (titanium, stainless steel or ceramic) dish which will beinsert molded pressed, or bonded into the base of the port reservoir toprevent potential penetration of needles through the base of a typicalstyle plastic port. Also advantageously, the port of the presentinvention features a titanium shield molded into a plastic port toparound the rubber septum to prevent needle mislocation, false needlelocations and potential medication misdirection. The port septums haveincorporate in them indication features to distinguish which portreservoir the surgeon or nurse is accessing and better locates thereservoir center. These features are utilized in other dual lumen portsby an indication on the port itself, but not on the septum.

Other features and advantages of the present invention will becomeapparent as the following Detailed Description proceeds, and uponreference to the Drawings, wherein like numerals depict like parts, andwherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1D depict various views of the preferred dual-port implantableaccess device of the present invention;

FIGS. 2A-2E depict various views of the preferred single-portimplantable access device of the present invention;

FIG. 3A-3D depict various views of another embodiment of the implantableaccess device of the present invention;

FIG. 4 depicts an alternative embodiment of the cup member of FIGS. 1-3;and

FIGS. 5A and 5B depict views of another alternative embodiment of thecup member of FIGS. 1-3.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 1A-1D depict various views of the preferred dual-port implantableaccess device 10 of the present invention. The port 10 generallycomprises a housing member 12 defining fluid chambers 22A and 22B. Thechambers are sealed by the housing 12, bottom cup members 14A and 14B,and self-sealing septum members 16A and 16B. In this embodiment, thehousing 12 is preferably formed of titanium, stainless steel, ceramic,and/or other biocompatible material. The septum 16A and 16B ispreferably formed of silicon or other semi-permeable materials thatpermit ingress and egress of needles to deliver fluid to the chambers22A and/or 22B. An exit port 18 is provided in communication withchambers 22A and 22B, which delivers fluid out of the chambers 22Aand/or 22B to a predetermined location, via stem 20 and attachedcatheter (not shown), as is understood in the art.

The septums 16A and 16B are formed with a generally circular shape, and,as shown in the drawings, may include a nipple 26 or a concave portion28 on the outer surface thereof. The nipple is advantageous for visualand/or tactile location of the port device 10, and as a locator forneedle insertion. Likewise, concave portion 28 provides similarfeatures, but may be used in areas where a protruding nipple isundesirable. The septums 16A and 16B and housing 12 are preferablyformed with mated tongue and groove portions, as shown in the side viewdrawings of FIGS. 1A and 1C. The housing may further include molded topmember 24 which press against the septum for further stability.

As opposed to plastic materials used in the prior art, the bottom cupmembers 14A and 14B are preferably formed of titanium or stainless steelto resist scratches and/or debris from being introduced into thechambers, as a result of needle impacts thereon. Preferably, bottom cupmembers 14A and 14B are attached to housing 12 via insert molding,interference fit, ultrasonic weld, biocompatible glue, and/or otherattachment means. FIGS. 2A-2E depict a single-port version of the portdevice of the present invention, and is similarly constructed as shownin FIG. 1A-1D.

FIG. 3A-3D depict another embodiment of the port device of the presentinvention. In this embodiment, the cup member 14′ includes sidewallportions 28 that are dimensioned to fit within the chamber 22′, definedby housing 12′. The cup member 14′ is attached to the housing 12′ byinsert molding, interference fit, ultrasonic weld, biocompatible glue,or other attachment means known in the art. The septum 16′ is similar tothe septum 16A and/or 16B and may also include a nipple or concaveportion, described above. In this embodiment, a metal ring 30 isprovided which circumscribes the top of the housing 12′ and ispositioned above the septum 16′. The ring 30 preferably includes flangemembers 32, which have an upper surface dimensioned so as to urge aneedle downward toward the septum, thus preventing errant entry ofneedles within the septum. In this embodiment the ring structure isformed of titanium, stainless steel or ceramic material for increasemechanical resistance to puncture and/or tear. Accordingly, since thering member 30 will protect the other components, the housing can beformed of less expensive material, e.g., plastics, etc. The ring member30 and housing 12′ preferably include mated tongue and groove portionsto hold the ring member securely against the housing, as shown.Additionally, the lower surface of the flange members 32 are dimensionedso as to force against the septum, thereby holding the septum in place.

FIGS. 4 and 5A-5B depict alternative embodiments for the cup memberdescribed above in FIGS. 1-3. In the embodiment of FIG. 4, the cupmember 14″ defines an exit port 18′ therein, and preferably located atthe bottom portion of the cup 14″, as shown. A stem 20′ is connected tothe port 18′ at one end, and a catheter 36 is connected to the other endof the stem 20′. So as to provide a low-profile shape, it is preferredthat the stem 20′ includes an elbow, or angled portion, to direct fluidsideways away from the port, as shown. In FIGS. 5A and 5B, the cup 14′″is formed with a flange 40 to define an opening 38 that is dimensionedto accept a stem 20″ therein. The cup 14″ and/or 14′″ are provided tobetter anatomically fit into the subcutaneous areas around muscletissue, and each are connected to the housing (not shown) in a mannersimilar to the embodiments of FIG. 1, 2 or 3.

Thus, it is apparent that there has been provided an implantablevascular access device that satisfies the objectives set forth herein.Those skilled in the art will recognize that the present invention issubject to modification and/or alterations, all of which are deemedwithin the scope of the present invention, as defined in the appendingclaims.

1. An implantable access port, comprising a plastic housing membercomprising a first side wall portion of at least one fluid chamber andan exit port in the side wall in fluid communication with said fluidchamber, a permeable septum member attached to said housing and defininga top of said fluid chamber, and an insert member comprising aconcaved-shape having a base portion covering a bottom of said fluidchamber, an edge radius extending generally outwardly from said baseportion generally towards said permeable septum member, and a secondside wall portion of said fluid chamber extending from said edge radiusonly to a point at or below said exit port of said fluid chamber,wherein said insert member comprises a material selected from the groupconsisting of stainless steel, titanium or ceramic, and wherein a volumeof said at least one fluid chamber is defined by said permeable septum,said first side wall portion of said plastic housing member, said secondside wall portion of said insert member and said base portion of saidinsert member.
 2. A port as claimed in claim 1, said septum furthercomprising a tactile or visual location marker portion on the outersurface thereof.
 3. A port as claimed in claim 1, wherein said septum isformed of silicone, and permits the ingress and egress of needles todeliver fluid to said fluid chamber.
 4. A port as claimed in claim 1,wherein said housing is dimensioned so as to be placed within apredetermined position under skin.
 5. A port as claimed in claim 1,wherein said tactile or visual location marker portion of said septumcomprises a nipple on the outer surface thereof.
 6. A port as claimed inclaim 1, wherein said tactile or visual location marker portion of saidseptum comprises a concave portion on the outer surface thereof.
 7. Aport as claimed in claim 1, wherein said edge radius is greater than0.035″.
 8. An implantable access port, comprising a plastic housingmember comprising a first side wall portion of at least one fluidchamber and an exit port in the side wall in fluid communication withsaid fluid chamber, a permeable septum member defining a top of saidfluid chamber; at least one ring circumscribing a top of said housingmember above said permeable septum, said at least one ring configured tobe secured to said plastic housing member and comprising flange membershaving an upper surface which tapers inwardly towards said permeableseptum such that at least one apex of said tapered flange members isdisposed at or below said permeable septum, said flange membersconfigured to urge a needle toward said permeable septum, said at leastone ring further configured to secure said permeable septum to saidport; and an insert member comprising a concaved-shape having a baseportion covering a bottom of said fluid chamber, an edge radiusextending generally outwardly from said base portion generally towardssaid permeable septum member, and a second side wall portion of saidfluid chamber extending from said edge radius only to a point at orbelow said exit port of said fluid chamber, wherein said insert membercomprises a material selected from the group consisting of stainlesssteel, titanium or ceramic, and wherein a volume of said at least onefluid chamber is defined by said permeable septum, said first side wallportion of said plastic housing member, said second side wall portion ofsaid insert member and said base portion of said insert member.
 9. Theport of claim 8, wherein said at least one ring and said housingcomprise mated tongue and groove portion configured to secure said atleast one ring to said housing.
 10. The port of claim 9, wherein said atleast one ring comprises a metal ring.
 11. The port of claim 9, whereinsaid at least one ring comprises a material selected from the groupconsisting of titanium, stainless steel or ceramic material.
 12. Theport of claim 8, wherein a lower surface of said flange members isconfigured to secure said permeable septum to said port.
 13. Animplantable access port, comprising a plastic housing member comprisinga first side wall portion of at least one fluid chamber and an exit portin the side wall in fluid communication with said fluid chamber, apermeable septum member attached to said plastic housing member anddefining a top of said fluid chamber; at least one ring circumscribing atop of said housing member above said permeable septum, said at leastone ring configured to be secured to said plastic housing member and tocomprising flange members having an upper surface which tapers inwardlytowards said permeable septum such that at least one apex of saidtapered flange members is disposed at or below said permeable septum,said flange members configured urge a needle toward said permeableseptum, said at least one ring further configured to secure saidpermeable septum to said port and to include a material selected fromthe group consisting of metal or ceramic material; and an insert memberdefining a bottom and a second side wall portion of said fluid chamber,wherein said insert member comprises a material selected from the groupconsisting of stainless steel, titanium or ceramic, and wherein a volumeof said at least one fluid chamber is defined by said permeable septum,said first side wall portion of said plastic housing member, said secondside wall portion of said insert member and said base portion of saidinsert member.
 14. The port of claim 13, wherein said at least one ringand said housing comprise mated tongue and groove portion configured tosecure said at least one ring to said housing.
 15. The port of claim 13,wherein a lower surface of said flange members is configured to securesaid permeable septum to said port.
 16. The port of claim 13, whereinsaid at least one ring comprises a metal ring.
 17. The port of claim 16,wherein said at least one ring comprises a material selected from thegroup consisting of titanium or stainless steel.
 18. The port of claim13, wherein said at least one ring comprises a ceramic ring.